Although I couldn't find any fix for this problem, I decided to give Minitube another try even though it too had similar issues in the past which is the reason I switched to Gmediafinder.

Since then Minitube 1.8 has been released and a fix for it was posted which basically requires more restricted extras to be installed and renaming the libgstvideoparsersbad.so plugin.

Apparently the libgstvideoparsersbad.so plugin has a bug that creates a problem with the playing videos and the person who posted it didn't explain why, but I guess it doesn't really matter just as long as it fixes Minitube.

Before installing minitube, you must first install the plugins followed by renaming libgstvideoparsersbad.so.